Engine starter gearing



March 8, 1949; D, L, MILLER 2,464,182

ENGINE STARTER GEARING Filed May 17. 1944 INVENTOR.

g0 a z whines/s: BY ii/W W ATT RNEY' Patented Mar. 8, 1949 UNITED STATES ZPATENT OFFICE ENGINE sran'rnn enannvo Application May 1'7, 1944, Serial No. 536,013

The present invention relates to engine starter gearing and more particularly to a drive of the automatic meshing and demeshing type having provision for holding the gearing in mesh until the engine is reliably self-operative.

It is an object of the present invention to provide a novel starter drive of the above type which is efficient and reliable in operation while being simple in construction and formed as a self contained unit.

It is another object to provide such a device in which the means for holding the pinion in mesh is positive in its action and is independent of the speed of rotation of the drive.

It is a further object to provide such a device in which the holding means is released in response to deceleration of the starting motor.

Further objects and advantages will be apparent from the following description taken in. connection with the accompanying drawing which:

Fig. 1 is a side elevation partly in section of a preferred embodiment of the invention;

Fig. 2 is a section on the line 22 of Fig. 1 showing the positions of the parts when the pinion is in mesh with the engine gear;

Fig. 3 is a View similar to Fig. 2 showing the parts in the positions assumed during deceleration of the drive, and

Fig. 4 is a detail in perspective of the latch tripping element.

In Fig. 1 of the drawing there is illustrated a power shaft I which may be the armature shaft of a starting motor not illustrated. Shaft l is provided with a reduced extension 2, the reduction in diameter forming a shoulder 3 against which thrust collars 4 are preferably seated. The outer end of the extension 2 of the power shaft has fixed thereon a driving head 5 in any suitable manner as by means of a cross pin 6 retained by a lock ring I. The driving head 5 has a smooth cylindrical portion 8 on which is slidably journalled a screw shaft 9.

Means for yieldably connecting the screw shaft 9 to the driving head 5 for limited relative rotary and longitudinal movement is provided comprising a spring ll anchored to the driving head by means of an anchor plate 12, and to the screw shaft by means of an anchor plate 13. The anchor plates are provided with non-circular openings conforming to similarly formed portions of the driving head and screw shaft, and are provided with slots for receiving the outturned ends I5, and I6 of the spring ll, respectively.

A pinion i7 is slidably journalled on the extension 2 of the power shaft for movement into and out of mesh with a gear [8 of an engine to be started, the meshing position of the pinion being defined by its engagement with the thrust collars t. Means for actuating the pinion is provided comprising a nut l9 threaded on the screw shaft 9 fixedly mounted as indicated at 2i in one end of a barrel member 22. The opposite end of the barrel 22 has fixed therein a driving clutch member 23 having overrunning clutch teeth E l adapted to engage the similar teeth 25 of a driven clutch member 26 fixed in any suitable manner on. the hub of the pinion ll. Separation of the clutch members 23, 26 is limited by a thimble 2i retained in the end of the barrel 22 by a lock ring 23, and bearing loosely on the hub of the pinion il against a shoulder 29. Means for normally holding the clutch members in engagement is provided in the form of a spring 3! located between the thimble and the driven clutch member 26.

According to the present invention, means are provided for positively holding the pinion. I! in mesh with the engine gear l8 until the engine is reliably self-operative. As here shown, this means comprises a latch member 32 pivotally mounted at 33 in the nut l9 and arranged to engage a notch 3 in the screw shaft under the 'T impulsion of a spring 35. The notch 34 is so located that the latch engages the bottom of the notch when the nut l9 has backed away from its most advanced position sufficiently to allow the teeth of the clutch members 23, 2s to disengage so that the pinion ll may overrun the drive.

Means for relasing the latch responsive to deceleration of the drive is provided in the form of an inertia ring member 36 swiveled on the nut 19, and retained thereon by suitable means such as a lock ring 31'. The ring 36 has fixed thereon as indicated at 38 a finger 39 having a cam surface 4! adapted to engage the end of a radial projection 32 on the latch 32 and thereby withdraw the latch from the notch 34 in the screw shaft. Relative rotation of the release ring 36 on the nut is is limited by suitable abutments 43, M fixed on the barrel in the path of the finger 39, the abutment 43 defining the idle position of the trip finger 39, and the abutment 44 defining its position when efiective to trip the latch 32.

In operation, energization of the starting motor causes rotation of the power shaft I in the direction of the arrow in Fig. 1 which rotation is transmitted through the spring H to the screw shaft 9. The nut I9 is thereby caused to traverse to the right and move the pinion [1 into mesh with the engine gear 18 until stopped by engagement with the thrust collars 4. As the nut approaches the end of its traversal, the latch 32 drops into the notch 34 in the screw shaft as shown in Fig. 2, thus preventing retrograde movement of the nut.

When the pinion I1 is stopped by the thrust collars 4, the longitudinal pressure of the barrel 22 forces the driving clutch member 23 against the driven clutch member 25 whereby the pinion is positively connected to the barrel 2 2 for rotation therewith.

When the engine fires, the acceleration of the engine gear It causes the pinion M to overrun the drive, which rotation is transmitted through the clutch members 26, 23 to the barrel 22 causing the nut !9 to back away sufficiently to permit disengagement of the teeth 24., 25 of the clutch members so as to allow the pinion l? to overrun the drive. Further backward movement of the nut is prevented by engagement of the latch 32 in the bottom of notch Bil in the screw shaft so that the pinion is held in mesh with the engine gear. If the engine should fail to continue selfoperative, cranking will be resumed. as soon as the speed of the engine gear it is reduced to correspondence with the speed of rotation of the drive by the starting motor, reengagement of the clutch teeth 24, 25 being assured by the pressure r of spring 3!. When a reliable start is secured, deenergization of the starting motor by the operator causes deceleration of the drive whereby the inertia of the ring 3% causes the finger as to ride up on the projection ll! of the latch, thus in Fig. 3. The nut 19 with its associated parts is then free to be returned to its idle position by the continued deceleration of the armature shaft.

If deemed desirable the natural deceleration of the armature shaft due to internal friction may be increased by any suitable braking means such as shown in Figure 12 of the patent to Janes, 2,167,891, August 1, 1939.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and various changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the claims appended hereto.

What is claimed is:

1. In an engine starter drive a power shaft, an engine engaging member, means responsive to acceleration of the power shaft for moving said member into engagement with a member of an engine to be started, a spring pressed latch for holding said member in engagement, and a release-member rotatably mounted on'the. drive and arranged to rotate thereon so as to engage and trip the latch responsive to deceleration of the power shaft.

2. In an engine starter drive a screw shaft a nut threaded thereon, a pinion, means connectingthe pinion to the nut for longitudinal move- 5' ment into and out of mesh with a gear of an engine to be started, a spring pressed latch for holding the. pinion in mesh and a ring journalled on the nut having a cam projection adapted to enage and trip the latch when the ring overruns the control nut due to-deceleration of the control uni-t.

An engine starter drive comprising a. power shaft, a pinion thereon movable into and outof mesh with the gear of an engine to be started; means for transversing and rotating the pinion from the power shaft including a screw shaft connected to rotate with the power shaft, a nut threaded thereon, and an over-running clutch between the nut and pinion; means including a latch member mounted on the nut andengagea'ble with the screw shaft for holding the pinion in mesh with the engine gear, and a release memleer having a lost motion connection with the nut member, movable thereon responsive to deceleratii tion of the nut member toengage and release the withdrawing the latch from the notch 3 as shown latch member.

DONALD L. MILLER.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATIENTS Number Name Date 2,332,055 Buxton Oct. 19, 1943' 2, 42,097 Estey Feb. 15, 19,44 2,344,463 Janes Mar. 14 1944 2,407,132 Buxton Sept. 3, 1946; 

